In recent years, the use of electronic money has become widespread. In electronic money, amount information called value is related to money value and fund settlement is performed by increasing or decreasing it.
In general, the user accesses a payment terminal installed in a store from his/her portable terminal by short-distance radio communication (near field radio communication) and gets payment processing by value.
For payment by value, there are a center management-type scheme by which the balance of value is stored in a database on the server's side and is reduced by access to the server at the time of payment and a stored value-type scheme by which an IC chip storing the balance of value is built into a portable terminal and payment is made by reducing the balance.
In the past, due to constraints of the communications capacity of the network, the stored value-type scheme by which the balance of value is stored in an IC chip of a portable terminal and payment is made locally between it and a payment terminal has been the mainstream; however, since the recent communications capacity of the network has been remarkably improved, it is expected that the center management-type scheme will become popular.
Therefore, it is expected that a portable terminal that complies with both schemes, the portable terminal having a built-in IC chip storing the balance of value and being capable of making payment also by the value balance on the server's side, will become widespread.
As described above, when a portable terminal that complies with both schemes is used, it would be convenient for the user if the value on the server's side can be transferred to the IC chip or the value stored in the IC chip can be transferred to the server's side.
As the technology to transfer the value on the server's side and the value on the IC chip's side bidirectionally, that is, the technology to store value on the server's side and on the IC chip's side and transfer the value on the server's side to the IC chip and transfer the value on the IC chip's side to the server, there is an “electronic trading system” of Patent Document 1.
This technology fills the value on the IC chip's side with the value stored on the server's side and adds the value stored on the IC chip's side to the value on the server's side at the time of payment.